The objective of this research proposal is to analyze the nature of the pulmonary vascular response to hemorrhagic shock and trauma. The studies outlined will characterize the total as well as the regional pulmonary hemodynamic and functional adjustments following hemorrhagic shock and non-thoracic trauma under standardized controlled conditions in the intact dog. The research will attempt to determine and place into perspective the roles of the postulated factors: (1) pulmonary thromboembolization, (2) adrenergic mechanisms, (3) pulmonary hypoperfusion, and (4) blood gas and pH derangements in the pulmonary adjustments and in the etiology of pulmonary insufficiency following shock and trauma. The methodology employed includes physiological, histological and isotopic techniques. It is hoped that the proposed interdisciplinary studies pooling physiological, engineering, and surgical expertise will lead to a better understanding of the basis of pulmonary adjustments and of pathophysiology of respiratory insufficiency following shock, thereby leading to a more meaningful approach to the management of a patient in pulmonary insufficiency.